1. Field of the Invention
The present invention relates to a fan device mounted in a refrigerator.
2. Description of the Related Art
In general, a refrigerator has a fan device which is mounted in an upper rear portion of the space inside the refrigerator for the purpose of supplying cold air into a freezing room and a refrigerating room.
Such a fan device has a hollow wall composed of a fan louver forming a front wall and an evaporator cover forming a rear wall. An air suction opening is formed substantially in the center of the evaporator cover, and a fan having an axial-flow blower is disposed in alignment with the suction opening and held by a motor cover. The fan induces cold air behind the hollow wall into the hollow wall. The fan louver has a plurality of forward air outlet slots which are substantially equally distributed upward and downward and to the left and right so as to uniformly distribute the cold air forwardly therethrough from the hollow wall into the freezing room. The evaporator cover has also a rearward air outlet for rearwardly discharging air from the hollow wall. The rearward air outlet is offset to the left or right from the air suction opening for a reason concerning the construction of the refrigerator. A fan duct is connected to the rearward air outlet so that the cold air in the hollow wall is blown into the refrigerating room through this fan duct.
A returning duct is formed on the rear side of the freezing room and the refrigerating room. The air blown through the forward air outlet slots into the freezing room cools the freezing room and then flows into the returning duct. The air blown into the refrigerating room though the rearward air outlet and the fan duct cools the refrigerating room and then flows into the returning duct.
The air collected in the returning duct is induced upward by the fan through a heat exchanger in a refrigeration cycle so as to be cooled and the cooled air is again blown into the hollow wall by the fan. The share or distribution of air to the forward and rearward air outlets, as well as layout of these air outlets, is determined in accordance with the results of test operations of the refrigerator.
The forward air outlet slots open uniformly to the left and right and upward and downward by the design of the fan louver. However, the rearward air outlet is located on the left or right side of the central air suction opening so that a difference is caused in the flow resistance to the air between the left and right portions of the fan louver which is provided with the forward air outlet slots, so that the flow of air tends to be concentrated to a local portion of the forward air outlet slots. Furthermore, since the motor cover is provided on the upper side of the fan, air does not flow toward the fan from the upper side thereof. In addition, the fan duct provided on the left or right side of the fan interrupts the flow of air flowing into the fan. In consequence, the fan induces air mainly from the left or right lower rear quarter of the fan.
When the fan induces air from, for example, left lower rear quarter thereof, the fan discharges the air to the right front upper quarter thereof. If the fan can perform its expected function, a spiral flow of air with no disturbance would be formed along the axis of the fan. Actually, however, the flow of air discharged from the fan is undesirably offset to the right side. This also causes an offset in the fluid dynamical force acting on each fan blade, resulting in a reduction of efficiency of the fan, as well as a generation of noise.
The air strongly blown to the right, upper front side of the fan tends to flow towards the rearward air outlet along an arcuate path so as to collide with air which flows to the right along the upper edge of the evaporator cover from the left upper side of the fan. It is therefore impossible to efficiently introduce the air from the fan towards the rearward air outlet. Since the blowing of air through the rearward air outlet is hampered, the air blown by the fan tends to directly reach the forward air outlet slots so that the noise generated by the fan propagates forwardly through the forward air outlet slots.
In addition, collision of flows of air flowing in different directions occur at the right side of the fan so as to cause a loss, with the result that the air blowing efficiency is further decreased.